Avaliação in vitro e in vivo de Nanoemulsão de Clorexidine

Abstract

Antisepsis is the process that results in reduction of microorganisms present in tissues by the use of antiseptics, the more used are those which have iodophors, chlorehxidine and alcohol. Chlorexhidine is widely used and recommended as a topical antiseptic but resistance reports to these antiseptic are becoming common and strategies are needed either to maximize the effect or development of new formulations to follow the mechanisms of acquired resistance of bacteria. We have in the nanoparticles an alternative, since the development of formulations with microbicide or microstatic effect is an option to conventional formulations with free molecule. The aim of this study was the characterization of an 0,25% aqueous-based chlorhexidine nanoemulsion (NM-Cl) and to evaluate by in-vitro and in vivo study its antiseptic effect. The NM-Cl presented adequate physicochemical characteristics for a nanoemulsion and presented antiseptic effect in the microdilution study, having the best effect between the tested formulations. In the Kill curve study there was a slower effect of the nanoemulsions but that was maintained for longer time when compared to chlorhexidine with free molecule. The nanoemulsion groups four-fold of MIC were the formulations with the most durable effect of those tested, presenting residual effect until T6 for both bacteria tested. At the in vivo study both formulations had a reduction of the microorganisms in the skin of the rats (p <0.0001) and as no difference of action was detected between the formulations in the tested times, we demonstrated the effect of the NM-Cl as an antiseptic (p > 0,05). NM-Cl presented satisfactory results at in vitro and in vivo tests despite being a formulation with lower concentration of chlorexhidine than the commercial formulation that is recommended for pre-surgical antisepsis. With this results, we have a nanostructured formulation with adequate physicochemical characteristics, antiseptic effect and residual antiseptic effect that are even better than the formulation with free molecule in the in vitro study and similar in vivo assay. Due to different mechanism of action, the NM-Cl has potential to avoid the resistance mechanisms of bacteria, being an alternative for formulation with free molecule. The NM-Cl is a viable antiseptic and potentially cheaper formulation, because of the similar effect with lower concentration of chlorexhidine.